Retired solicitor accused of drink- driving claimed he was innocent because his girlfriend, a married senior policewoman, was at the wheel.

Colin McKenzie, 60, added that she was probably over the alcohol limit at the time.

But to protect her marriage and career, he said, he could not possibly reveal her name.

His claims led to speculation that someone in the higher echelons of Devon and Cornwall Police had been having an affair behind her husband's back and driving her lover's car while drunk.

However, Exeter magistrates threw out his excuse and indicated they did not believe the woman existed outside his imagination.

They convicted him of being one and a half times over the drink driving limit and banned him for a year.

McKenzie was arrested after an anonymous tip-off that he was in a pub and about to drive to his isolated home three miles away in the hamlet of Shillingford St George.

Police lay in wait and chased the Jeep Cherokee for five minutes at up to 50mph on single-track roads. They lost it when it turned on to a mud track where their twowheeldrive patrol car could not follow.

A short while later, the Jeep was found abandoned near McKenzie's home and a dog tracked him through a field, a farm yard and into a copse. It flushed him out and bit him when he refused to stop.

Later, McKenzie claimed he had deliberately led the police dog on a false trail, and then lied to officers about having walked home from the pub, to give his lover time to escape.

"I am a bachelor and I have a lot of lady friends who are very close,' he said. 'I was with one that evening.

"I have known her since 1987 and I saw her regularly but not as regularly as I would like. We had an intimate relationship.

"I cannot name her because she is a senior member of the constabulary and she is married. If she had been arrested, her career in the police would end if she was over the limit, which she may have been.

"It would have devastated her marriage. She would not have been able to explain what she was doing at my place at that time of the morning.

"There is nothing that would prevail on me to name her."

He claimed the woman panicked when the chase started a n d deliberately went up the muddy lane to shake off police.

However the patrol car driver, PC Raymond Tribe, played a video of the five-minute pursuit and said he was sure there was only the driver in the vehicle.

He said he had a clear view inside as it turned into side lanes and could see there was no passenger.

Dog handler PC Gareth Rees added that his dog Magnum had picked up only one scent from the driver's door and had followed it until McKenzie was arrested.

He said the dog was trained to show if there was more than one scent.

PC Rees admitted the dog had been put down two months later, after savaging his sergeant during a training exercise, but said there were never any problems with his tracking.

Banning McKenzie and ordering him to pay a total of £1,064, magistrates' chairman Liz Rumsby told him: "We found the evidence of the police officers was credible and that of the dog handler was compelling. They corroborated each other.

"We found your evidence not credible and felt there were inconsistencies, in particular regarding the protection of another's reputation.

"One instance of this is that, being conscious of the lady's position, you say you allowed her to drive your vehicle despite believing her to be over the limit."

A spokesman for Devon and Cornwall Police said: "He was entitled to have his day in court and it was up to him to satisfy the magistrates.

"The fact that he has been convicted suggests the validity the magistrates gave to his explanation. It was a case of 'nice try but no cigar'."

He added he did not believe any of the force's senior policewomen - who include an assistant chief constable - had anything to worry about.